John Brennan says officials were well aware of sizable opposition to President Recep Tayyip Erdogan

MCLEAN, Va.—Central Intelligence Agency Director John Brennan said intelligence officials were well aware of strains within Turkey and sizable opposition to President Recep Tayyip Erdogan, but he wouldn't say whether they foresaw an attempted coup last week.

Mr. Brennan, speaking Tuesday evening to an audience at the Intelligence and National Security Alliance, described the setting U.S. officials were in Friday night when the attempted coup was unfolding.